The major challenge facing Pfs25-based TBV development is to find a formulation with great safety profile and capable of inducing sustained high antibody responses. Previously the LMIV has demonstrated that conjugating Pfs25 with carrier protein ExoProtein A (EPA) of Psuedomonas aeruginosa greatly enhance the immunogenicity of the recombinant Pfs25 produced in Pichia pastoris. A process was developed to conjugate Pfs25 with rEPA, and cGMP-grade Pfs25-EPA conjugate was manufactured and formulated with Alhydrogel. A Phase 1 trial was conducted in US. After demonstrating that vaccine was safe, immunogenic, and could induce transmission reducing activity in US vaccinees, LMIV has now completed a Phase 1 trial in Mali, the first time in the world evaluating the safety, immunogenicity, and transmission blocking activity of a vaccine in a target population. The results of these studies have demonstrated that transmission blocking activity can be induced in both US and Malian vaccinees. However, the antibodies induced by this vaccine when formulated with Alhydrogel are short-lived, and hence improvements to the vaccine are required to achieve the activity thought to be needed for malaria elimination campaigns.